Invasive species are a topic of considerable global relevance. There are the Asian carp that people are working hard to keep out of the Great Lakes, for instance. There is also the rather large question of what sort of inter-ocean migrations will occur as the result of the loss of summer sea ice in the Arctic. If orca whales migrate into the Atlantic (as Alun Anderson predicts), life will become rather more dramatic for a lot of seals in Newfoundland. Shipping is one major mechanism through which species from one place can end up in another, where they cause ecological problems.

When I worked at the Science Al!ve daycamp at Simon Fraser University, I remember one ecology graduate student who was waging a dedicated campaign against a particular invader: the black licorice slug (Arion rufus). She used to put them in her pockets when she found them and then throw them into ponds when the opportunity arose.